The concept of infrared imaging for biomedical applications has been explored for some time. The early technology used, unfortunately, had neither the sensitivity, resolution nor speed to be of substantial value. Infrared imaging has now advanced to where it is being used for a range of applications in medicine, and has multiple advantages over conventional medical imaging techniques, including, low cost, no ionizing radiation and no need for contrasting agents. However, these medical imaging systems are limited to collecting and displaying tissue physiology in a single band (i.e., wavelength spectrum) of emission. They display only information pertaining to, for instance, the infrared flux at a single band but cannot display the same image in the visible band or in multiple infrared bands.
There are commercially available systems, at the present time, that permit analysis of multiple bands of light. Spectrophotometric methods are being used to non-invasively monitor oxygen saturation, glucose levels, and the concentration of other blood constituents, for instance, nitrous oxide and carbon dioxide. Spectrophotometric methods are also being used to non-invasively monitor oxidative metabolism of body organs in vivo by using measuring and reference wavelengths in the near-infrared region. Unfortunately, these approaches do not generate a two dimensional (2-D) or three dimensional (3-D) spatial image in connection with the tissue characteristics being monitored or evaluated.
The ability to measure different light spectra can provide unique information about the substances or constituents being monitored. To the extent that an image of the tissue characteristic or the constituents being monitored can be generated, such would provide an added advantage for a variety of medical applications. One approach has been to obtain measurements from an object being imaged using two different detectors at the same time. However, such an approach requires that the angle of view be different for each of the two detecting systems. As a result, the reconstruction, for instance, of a merged image may be difficult.
To avoid the issues associated with different angles of view, single lens systems have been designed to collect different light spectra from the object being observed. However, the single lens solution tend to encounter problems with image degradation, while at the same time being expensive and cost prohibitive.
Alternatively, it is possible, using a filter wheel, to view co-incident but not concurrent images of the same object at different frequencies. An additional limitation to this approach can be the sensitivity range of the single detector that is typically used.
Accordingly, it would be advantageous if multiple bands of lights, such as those in the infrared and visible spectra, being emitted from a target or object being monitored or observed, can be evaluated and analyzed, while images from such spectra can be simultaneously integrated and displayed in real time.